The present invention pertains to an actuating pedal for the brake system of a road vehicle with a fastening device for fixing the actuating pedal in a pivot bearing on a pedal block of the vehicle, which said pedal block is a rigid part of the body, with a connection device to a brake power booster module, with a pedal body, and with an actuating surface.
Actuating pedals of this class described in the introduction have been used in utility vehicles and motor vehicles for a long time. The actuating pedals have to meet high requirements concerning strength and the rigidity of the connection, and it should be borne in mind that extremely high forces are applied to the actuating pedal especially in panic or full braking situations.
In addition, high torsional rigidity is also desirable and necessary because a direct, good feeling of braking shall be provided at any time for the driver of the vehicle during the application of the actuating pedal.
Based on these requirements, all the actuating pedals used at present are made of steel without exception. Such a component is usually manufactured from a steel sheet, and the entire manufacturing process comprises a plurality of shaping processes and additional components, e.g., for mounting restoring springs or for actuating limit switches, are welded to the pedal body as a basic sheet metal part. The number of individual processing steps makes the production of actuating pedals of this class particularly expensive compared with other vehicle components despite automation engineering, because a final surface treatment in the form of a paint coating is usually additionally performed after the end of the shaping operation proper. In addition, the actuating pedals used in the prior art have the serious drawback that they have a relatively heavy weight because of their design, which may have a disadvantageous effect especially in case of an accident.
The object of the present invention is therefore to provide an actuating pedal of the type described in the introduction, which avoids the drawbacks of prior-art actuating pedals as known from the prior art. In particular, considerable cost savings shall be achieved in production. Moreover, the feeling of actuation during the braking operation shall be further optimized.
According to the present invention, an actuating pedal (1) for the brake system of a road vehicle is provided with a fastening device for fixing the actuating pedal in a pivot bearing on a pedal block of the vehicle. The pedal block is a rigid part of the body, with a pedal body and with an actuating surface. The pedal body has at least one inner metal core and a plastic jacket surrounding the metal core.
The design features of the actuating pedal according to the present invention ensure, on the one hand, the torsional rigidity and the high break loadability of the actuating pedal due to the use of an inner metal core and, in addition, the plastic jacketing makes possible an optimized shaping of the actuating pedal, and the entire manufacturing process can be carried out especially inexpensively by means of the hybrid technology. A large number of manufacturing steps are eliminated within the framework of the production and the final surface treatment of the actuating pedal according to the present invention is no longer necessary.
It is particularly advantageous for the fastening device for fixing the actuating pedal on a bracket which is a rigid part of the body to be made in one piece with the plastic jacketing within the framework of the jacketing of the metal core. The mounting points necessary for the pivoting of the actuating pedal can be integrated in the jacketing without problems according to the plastics injection molding technique.
Moreover, another advantage of the present invention is that additional attached elements, e.g., for the actuation of a brake light switch or the attachment of spring-restoring mechanisms can be integrated in the plastic jacketing without problems. Based on the unique shape, no additional special process and production steps are necessary for this for the injection operation for preparing the plastic jacketing.
It also proved to be expedient to design the metal core as a steel sheet core of a simple shape, which can be manufactured within the framework of an uncomplicated shaping operation. PA(Polyamide) 6 or PA 6.6/GF (glass fiber) is preferably used as the material for the plastic jacketing. In addition, the actuating surface can be applied to the pedal body by injection molding according to the two-component process, and the actuating surface receives a top layer consisting of polyurethane.
The design of the pedal body according to the present invention also makes it possible to provide the fastening device of the actuating pedal with a pin element, which has at its free end facing away from the fastening device at least one spring-tensioned pressure roller, which rolls on a corresponding curved path on the pedal block which is a rigid part of the body during the pivoting of the actuating pedal around the pivot mounting point of the fastening device. The curved path on the pedal block can be adapted correspondingly depending on the desired direction of the forces for returning the pedal, so that an optimal feeling of actuation is obtained for the driver of the vehicle. Moreover, the curved path may be designed such that the actuating pedal will be automatically free from clearance after the installation despite existing manufacturing tolerances, so that an immediate braking effect is guaranteed during the actuation of the brake system.
Moreover, it proved to be particularly advantageous for the pedal body to have an elongated hole, in which a connecting rod of the connection device is arranged displaceably, at the point at which the pedal body cooperates with the connection device to the brake power booster module. The design of the elongated hole causes an unlimited straight-line motion of the connecting rod, so that an additional ball-and-socket joint for providing additional degrees of freedom during the movement of the actuating rod may be eliminated. In addition, the pedal angle can be made greater and the length of the pedal can be reduced. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.